Templated Growth of FASnI3 Crystals for Efficient Tin Perovskite Solar Cell

Tin perovskite solar cells (TPSCs) are rising as the most promising candidates for lead-free PSCs. However, the randomly crystallized tin halide perovskite with high concentration of defects is still the bottleneck for obtaining high efficiency. Here, we report the pretreatment of FASnI3 (formamidinium, FA) perovskite film by spin-coating a solution of organic halide salt n-propylammonium iodide (PAI) before annealing. It is found that PAI can induce the templated growth of FASnI3 crystals by reconstruction of the intermediate phase, resulting in a highly crystallized FASnI3 film with preferential orientation along (100) plane and suppressed trap density. Finally, a stabilized efficiency of 11.22% was certified at an accredited test center and the cell is stable, maintaining over 95% of its initial efficiency after 1000 hours of operation at the maximum power point.